Control law for transformerless converters connected to the grid through an L filter

Abstract

This paper presents a control law for single-phase power converters, coupled to the grid by means of an L filter, aimed at active power injection. This control law makes use of an estimation scheme which obtains estimations of the filter parameters in order to cope with the compensation of timeperiodic signals arising in the error average model and with the possible existence of harmonics in the grid voltage. An evaluation of the proposed control law is performed by means of numerical simulations where a single-phase H-bridge inverter with unipolar pulse width modulation is used.

Analysis and Validation for an Inverter-side Current Controller in LCL Grid-connected Power Systems

“…Transformerless power inverters are connected to the grid through a passive filter. An inductive filter represents one of the simplest solutions for this connection, which leads to simple filter and controller designs, and practical implementations [4]. Most advanced solutions such as LCL or LLCL filters provide increased mitigation of switching harmonics with smaller components, reduced physical space and reduced costs [5], [6].…”